Protein / target

B-lymphocyte antigen CD20

MS4A1P11836Homo sapiensSwiss-Prot
Clinically validated
Therapeutic maturity
11
Approved medicines
30
Clinical trials
Small-molecule tractable
Druggability
Structure with Ligand

Protein at a glance

Biological role

Epidermal growth factor receptor binding

Primary system

Immune system

Strongest disease association

B-cell chronic lymphocytic leukemia

Clinical evidence · score 0.63

Therapeutic maturity

Clinically validated target

11 approved medicines against this target

Druggability

Small molecule

Open Targets tractability · Structure with Ligand

Clinical development

11 approved · 7 in clinical development

30 linked trials

Derived from structured UniProt, Open Targets and literature data on this page.

Protein profile

UniProt 2026_02

Canonical identity and biological annotation from UniProt.

Function

B-lymphocyte-specific membrane protein that plays a role in the regulation of cellular calcium influx necessary for the development, differentiation, and activation of B-lymphocytes (PubMed:12920111, PubMed:3925015, PubMed:7684739). Functions as a store-operated calcium (SOC) channel component promoting calcium influx after activation by the B-cell receptor/BCR (PubMed:12920111, PubMed:18474602, PubMed:7684739)

Subcellular location

Cell membrane
Domains and Gene Ontology detail (20)

Gene Ontology

  • Ccell surface
  • Cexternal side of plasma membrane
  • Cextracellular exosome
  • Cextracellular space
  • Cplasma membrane
  • Cplasma membrane raft
  • Fepidermal growth factor receptor binding
  • Fidentical protein binding
  • Fimmunoglobulin binding
  • FMHC class II protein complex binding
  • PB cell activation
  • PB cell differentiation

297 aa · 33 kDa · 2 isoforms

Biological roles

What this protein does, drawn together from its UniProt function, Gene Ontology terms and Reactome pathways.

Immune signallingGO
View supporting evidence

Immune signalling

  • ·B cell activation
  • ·B cell differentiation
  • ·B cell proliferation
  • ·B cell receptor signaling pathway

Concepts derived from UniProt GO Reactome — each badge above shows which sources supported that role.

Interaction neighbourhood

STRING v12.0

Proteins with the strongest functional or physical association. Node size and line weight reflect STRING confidence; hover or select a partner to inspect one association.

CD19MS4A3CD79ACD22IGKV2D…IGHV3-…POU2AF1CD79BBANK1TCL1AMS4A1

10 strongest partners — larger node and heavier line mean higher confidence

Functional and physical associations from STRING v12.0. Only associations with this protein are drawn — partner-to-partner links are not part of this evidence.

Drugs targeting this protein

2

Whether each drug engages this protein directly or through a complex, and how many other targets are recorded for it. Direct binders with few recorded targets are listed first.

ocrelizumab
Narrow target profileApprovedBinding agent

B-lymphocyte antigen CD20 binding agent

Appears in clinical studies involving multiple sclerosis, diffuse large B-cell lymphoma, relapsing-remitting multiple sclerosis, chronic progressive multiple sclerosis

Direct interaction with this protein · Only this protein recorded as a target

obinutuzumab
Narrow target profileApprovedBinding agent

B-lymphocyte antigen CD20 binding agent

Appears in clinical studies involving follicular lymphoma, B-cell chronic lymphocytic leukemia, B-cell chronic lymphocytic leukemia, B-cell chronic lymphocytic leukemia

Direct interaction with this protein · Only this protein recorded as a target

ChEMBL mechanism, action type and target identity. Open Targets clinical status and indications.

Translational evidence

Open Targets 26

Why this target matters therapeutically — disease associations, drugs in development, tractability and safety, from Open Targets.

Highest-confidence therapeutic associations

Diseases where a drug acting on this target has already reached clinical development.

multiple sclerosis0.99

Clinical · overall 0.61

rheumatoid arthritis0.99

Clinical · overall 0.61

B-cell chronic lymphocytic leukemia0.99

Clinical · overall 0.63

non-Hodgkin lymphoma0.98

Clinical · overall 0.61

follicular lymphoma0.98

Clinical · overall 0.62

Highest overall evidence

Remaining associations by Open Targets' aggregated evidence score.

diffuse large B-cell lymphoma0.62

Clinical

neoplasm0.59

Literature

acute lymphoblastic leukemia0.58

Clinical

granulomatosis with polyangiitis0.58

Clinical

relapsing-remitting multiple sclerosis0.57

Clinical

Show all associations
B-cell chronic lymphocytic leukemia0.63
diffuse large B-cell lymphoma0.62
follicular lymphoma0.62
rheumatoid arthritis0.61
non-Hodgkin lymphoma0.61
multiple sclerosis0.61
neoplasm0.59
acute lymphoblastic leukemia0.58
granulomatosis with polyangiitis0.58
relapsing-remitting multiple sclerosis0.57

Open Targets ranks 462 associations for this target and we store the top 10 by aggregated score. The long tail is largely literature co-mention and RNA-expression evidence, not evidence that this target drives those diseases.

Known drugs · 18 total

GLOFITAMABApproval

diffuse large B-cell lymphoma · neoplasm · diffuse large B-cell lymphoma

OBINUTUZUMABApproval

follicular lymphoma · B-cell chronic lymphocytic leukemia · B-cell chronic lymphocytic leukemia

UBLITUXIMABApproval

multiple sclerosis · relapsing-remitting multiple sclerosis · chronic progressive multiple sclerosis

TOSITUMOMAB 131IPhase 3

follicular lymphoma · follicular lymphoma · non-Hodgkin lymphoma

FBT-A05Phase 1 2

B-cell chronic lymphocytic leukemia · B-cell chronic lymphocytic leukemia · non-Hodgkin lymphoma

MT-3724Phase 2

diffuse large B-cell lymphoma · non-Hodgkin lymphoma · non-Hodgkin lymphoma

MOSUNETUZUMABApproval

follicular lymphoma · neoplasm · high grade B-cell lymphoma

TOSITUMOMABApproval

non-Hodgkin lymphoma · follicular lymphoma · follicular lymphoma

OCARATUZUMABPhase 2

non-Hodgkin lymphoma · follicular lymphoma · non-Hodgkin lymphoma

EPCORITAMABApproval

follicular lymphoma · B-cell non-Hodgkin lymphoma · diffuse large B-cell lymphoma

Tractability

SM · Structure with LigandAB · Approved DrugAB · UniProt loc high confAB · GO CC high confAB · UniProt SigP or TMHMMAB · Human Protein Atlas locPR · Database UbiquitinationPR · Half-life DataOC · Approved Drug

Clinical trials

30

Trials of drugs that target this protein — reached indirectly through those drugs, so a trial listed here studies the drug, not the protein.

Show remaining trials (24)

ENROLLING_BY_INVITATION · via ocrelizumab · NCT06495593

ClinicalTrials.gov via the drug-target graph.

Forefront confidence

Synthesis

Our own weighting of the evidence behind each disease association. Human genetics and clinical evidence count for most; literature co-mention counts for little, because two entities sharing an abstract is not evidence that one drives the other.

B-cell chronic lymphocytic leukemiaWell supported
0.78
agreement 0.640.91
Clinical84%Literature15%RNA expression1%

Open Targets aggregate 0.63 · 3 independent evidence families

diffuse large B-cell lymphomaWell supported
0.77
agreement 0.610.92
Clinical85%Literature15%

Open Targets aggregate 0.62 · 2 independent evidence families

follicular lymphomaWell supported
0.76
agreement 0.610.92
Clinical88%Literature12%

Open Targets aggregate 0.62 · 2 independent evidence families

rheumatoid arthritisWell supported
0.76
agreement 0.620.89
Clinical92%Literature8%RNA expression0%

Open Targets aggregate 0.61 · 3 independent evidence families

non-Hodgkin lymphomaWell supported
0.76
agreement 0.600.91
Clinical92%Literature8%

Open Targets aggregate 0.61 · 2 independent evidence families

The evidence agreement range shows how closely the independent evidence families agree — it is not a statistical confidence interval, and nothing here is fitted to outcome data. Derived from Open Targets evidence types under Forefront weighting; the underlying per-type scores are shown above so the calculation can be checked.

What's happening now

6

Recent activity around this target, drawn from one canonical event stream. Every item is reached through 2 drugs that target this protein, so each event is news about that drug rather than about the protein directly.

  1. Trial status changed2026-07-17

    A Phase 1b Open-Label Study to Evaluate the Safety and Anti-cancer Activity of Loncastuximab Tesirine in Combination With Other Anti-cancer Agents in Patients With Relapsed or Refractory B-cell Non-Hodgkin Lymphoma (LOTIS-7)

    Status changed to Active, not recruiting · ClinicalTrials.gov · via obinutuzumab

  2. New publication2025-07-11
    Effects of different B-cell-depleting strategies on the lymphatic tissue.

    Annals of the rheumatic diseases · 2025 · 7 citations · Europe PMC · via obinutuzumab

  3. Regulatory approval2018-01-08

    Approval: Ocrevus (EMA)

    ema · regulatory · ema · via ocrelizumab

  4. New publication2016-12-21
    Ocrelizumab versus Placebo in Primary Progressive Multiple Sclerosis.

    The New England journal of medicine · 2017 · 1,348 citations · Europe PMC · via ocrelizumab

  5. New publication2016-12-21
    Ocrelizumab versus Interferon Beta-1a in Relapsing Multiple Sclerosis.

    The New England journal of medicine · 2017 · 1,424 citations · Europe PMC · via ocrelizumab

  6. Regulatory approval2014-07-22

    Approval: Gazyvaro (EMA)

    ema · regulatory · ema · via obinutuzumab

Objective event titles are shown unmodified; the event kind and significance line are derived from structured fields. Forefront AttentionEvent stream aggregating Europe PMC Regulatory filings ClinicalTrials.gov.